The primary aim of this study was to examine the impact of temperature and fluid salinity on carbon dioxide (CO2) injectivity. The injectivity experiment was conducted using a core flooding unit with Berea sandstone representing the porous media and sodium chloride (NaCl) as the formation fluid. To assess the relative effect of temperature and salinity on CO2 injectivity impairment, the temperature of CO2 injection was varied from 27 to 100 °C, and the formation fluid salinity ranged from 6000 ppm to 100,000 ppm. CO2 injectivity alteration was determined by calculating the relative injectivity change (RIC) between the initial and final permeability. Results indicated that CO2 injection below the supercritical temperature had no effect on the RIC. However, CO2 injectivity showed a significant reduction of approximately 56.52% at 40 °C, with the reduction in impairment gradually decreasing to 32.2% at 100 °C. The findings also demonstrated that increased salinity led to more salt precipitation, which could narrow pore channels, ultimately reducing porosity and permeability, thereby affecting injectivity. This study is among the first experimental efforts to validate the relative effects of temperature and salinity on CO2 injectivity impairment. The insights gained from this research could enhance the understanding of CO2 injectivity impairment in deep saline reservoirs.